The Importance of Having Users

And so I inherited popclient. Just as importantly, I inherited
popclient's user base. Users are wonderful things to have, and
not just because they demonstrate that you're serving a need, that
you've done something right. Properly cultivated, they can
become co-developers.

Another strength of the Unix tradition, one that Linux pushes to
a happy extreme, is that a lot of users are hackers too. Because
source code is available, they can be effective
hackers. This can be tremendously useful for shortening debugging
time. Given a bit of encouragement, your users will diagnose
problems, suggest fixes, and help improve the code far more quickly
than you could unaided.

The power of this effect is easy to underestimate. In fact, pretty
well all of us in the open-source world drastically underestimated
how well it would scale up with number of users and against system
complexity, until Linus Torvalds showed us differently.

In fact, I think Linus's cleverest and most consequential hack
was not the construction of the Linux kernel itself, but rather his
invention of the Linux development model. When I expressed this
opinion in his presence once, he smiled and quietly repeated something
he has often said: ``I'm basically a very lazy person who likes to get
credit for things other people actually do.'' Lazy like a fox. Or,
as Robert Heinlein famously wrote of one of his characters, too lazy
to fail.

In retrospect, one precedent for the methods and success of
Linux can be seen in the development of the GNU Emacs Lisp library and
Lisp code archives. In contrast to the cathedral-building style of
the Emacs C core and most other GNU tools, the evolution of the Lisp
code pool was fluid and very user-driven. Ideas and prototype modes
were often rewritten three or four times before reaching a stable
final form. And loosely-coupled collaborations enabled by the
Internet, a la Linux, were
frequent.

Indeed, my own most successful single hack previous to fetchmail
was probably Emacs VC (version control) mode, a Linux-like
collaboration by email with three other people, only one of whom
(Richard Stallman, the author of Emacs and founder of the Free Software Foundation) I have met
to this day. It was a front-end for SCCS, RCS and later CVS from
within Emacs that offered ``one-touch'' version control operations.
It evolved from a tiny, crude sccs.el mode somebody else had written.
And the development of VC succeeded because, unlike Emacs itself,
Emacs Lisp code could go through release/test/improve generations very
quickly.

The Emacs story is not unique. There have been other software
products with a two-level architecture and a two-tier user community
that combined a cathedral-mode core and a bazaar-mode toolbox. One
such is MATLAB, a commercial data-analysis and visualization tool.
Users of MATLAB and other products with a similar structure invariably
report that the action, the ferment, the innovation mostly takes place
in the open part of the tool where a large and varied community can
tinker with it.